The present invention relates generally to an adaptive equalizer, and more specifically, an adaptive equalizer preventing deterioration of reception performance caused by intersymbol interference distortion and co-channel interference waves.
Conventionally, for example, when intersymbol interference and co-channel interference waves exist, a system to improve reception performance using space diversity and an equalizer is known, as disclosed in a paper titled "Co-channel Interference Performance of Diversity Equalization in Mobile Radio" by Hitoshi YOSHINO and Hiroshi SUZUKI, in 1992, The Autumn Meeting of The Electronic Data Academic Society on B-260.
As shown in FIG. 5, this system receives a plurality of signals from a plurality of antennas 500 and 510, equalizes and synthesizes these received signals in an equalizer 520, then performs demodulation. By using this system, reception performance despite co-channel interference waves is improved.
The improvement of reception performance despite co-channel interference waves, however, is obtained by space diversity. Therefore, in this case, there is a problem that the configuration of the receiver becomes complicated by the diversity.
On the other hand, in case of equalizing signals while estimating a channel impulse response, when a co-channel interference wave exists a channel impulse response estimator locks to the co-channel interference wave and estimates a different channel impulse response from the actual channel impulse response. As a result, the system equalizes reception signals with the wrong channel impulse response. Therefore, the reception performance of the system is greatly deteriorated.